Astroparticle Physics with AMS-02deboer/html/Talks/Paris_short.pdf · July, 20. 2004 COSPAR, Paris,...
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Transcript of Astroparticle Physics with AMS-02deboer/html/Talks/Paris_short.pdf · July, 20. 2004 COSPAR, Paris,...
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 1
Astroparticle Physics with AMS-02
AMS: Alpha Magnetic Spectrometer
2007/2008
Wim de Boer
on behalf of the AMS collaboration
University of Karlsruhe
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 2
Outline
• Physics Motivations
• Detector requirements
• Prospects for Indirect Dark Matter searches
• Conclusions
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 3
AMS Physics motivations
• Search for cosmic anti matter
• Search for Dark Matter
• Precision measurement on cosmic rays
• Gamma ray astrophysics
AMS will collect ~10AMS will collect ~101010 Cosmic Rays Cosmic Rays ((e±, γ , p±,3,4He,B,C, 9,10Be, elements Z<25 in Nearin Near--Earth Orbit from Earth Orbit from few GV to few TVfew GV to few TV
Reg
ion
of
antim
atte
r
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 5
WMAP determines WIMP annihilation x-section
Neutralino annihilation is a strong source of antiprotons, positrons and gammas by annihilation into quarks.
Thermal equilibrium abundance
Actual abundance
T=M/25
Com
ovin
g nu
mbe
r den
sity
x=m/T
T>>M: f+f->W+W; W+W->f+fT<M: W+W->f+fT=M/25: W decoupled, stable density(wenn annihilation rate < expansion rate, i.e. Γ=<σv>nχ < H !)
Jung
man
n,K
amio
nkow
ski,
Grie
st, P
R 1
995
Boltzmann equation:H-Term takes care of decrease in density byexpansion. Right-hand side:Annihilation and Production.
Present number density requires <σv>=2.10-26 cm3/s
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 6
Neutralino Annihilation Final States
B-fragmentation well studied at LEP!Yield and spectra of positrons,gammas and antiprotons well known!
BDominant Diagram for WMAPcross section:χ + χ ⇒ A ⇒ b bbar quark pair
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 7
Excess of Diffuse Gamma Rays above 1 GeV
Prel.A B C
D E F
Stro
ng, M
oska
lenk
o, R
eim
er, t
o be
pub
lishe
d
A: inner Galaxy (l=±300, |b|<50)B: Galactic plane avoiding AC: Outer Galaxy
D: low latitude (10-200)
E: intermediate lat. (20-600)F: Galactic poles (60-900)
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 8
Local electron and proton spectradetermine shape of gamma background
Solar modulation by solar winds important below few GeV
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 9
Excess of Diffuse Gamma Rays same in all directionsand compatible with neutralino mass of 50-100 GeV
Important: if experiment measures gamma rays down to 0.1 GeV, then normalizations of DM annihihilation and background can both left free, so one is not sensitive to absolute background estimates, BUT ONLY TO THE SHAPE, which is much better known.
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 10
Diffuse Gamma Rays for different sky regions
A B C
D E F
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 11
Longitude and latitude profiles
NFW profile
Isothermal Profile +disc enhancement
NFW profile excluded, isothermal profile perfect as expected often from rotation curves,see e.g. Jimenez, Verde and Oh, astro-ph/0201352. Asymmetry determines halo ellipticity.
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 12
Halo profile
x
z
y
ab
c
(α,β,γ) − define the slope ρ0 - local density 0.3-0.7 GeV/cm3
a -scale parameter (depends on ρ0) Isothermal profile: α,β,γ,a = 2,2,0,4
Ellips: x2/a2 +y2/b2 + z2/c2 = c
Isothermal core
NFW cusp
W. de Boer et al., to be published
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 13
EGRET excess interpreted as DM consistent withWMAP, Supergravity and electroweak constraints
0
WMAP
EGRET
Stau coannihilation
mAresonance MSUGRA can fulfill
all constraints from WMAP,LEP, b->sγ, g-2 and EGRET simultaneously, if DM is neutralino with massin range 50-100 GeV and squarks and sleptons are O(1-2 TeV)
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 14
Positron fraction and antiprotons from DM annihilation
SAME Halo and MSSM parameters as for GAMMA RAYSbut signal strong function of propagation model!
Positrons AntiprotonsAntiprotonsPositrons
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 15
Propagation in GALPROP compared with DarkSusy:LARGE DIFFERENCE
Spectrum after propagation of injection of 1-3 GeV source with NFW profilein DarkSusy (analytical solution of diffusion equation l) and GalProp (numericalsolution of diffusion equation including all physical effects, like reacceleration)
Antiprotons Positrons
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 16
Propagation models
Propagation model:- describes propagation (diffusion, convection, reacceleration) of cosmic
ray particles in galaxies- calculates nuclear interaction of primary produced particles with interstellar medium (ISM) Predicts abundances of element. Estimates backgrounds.
- considers local modulation effects, solar modulation.
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 17
Diffusion equation
Particle density:
Source function: with
Diffusion coefficient:
Convection velocity:Diffusive reacceleration:Momentum loss rate:Radioactive decay:Fragmentation:
GALPROP program by Moskalenko and Strong provides numerical solution to this diffusion eq. for equilibrium taking into account particle densities of ALL nuclei.
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 18
AMS-02 capabilities
BoronBeryllium Helium
1 year 1 day6 months1 year 6 months 1 day
10Be (t1/2=1.5Myr) / 9Bewill allow to estimate thepropagation time andsize of the ISM
B is secondary produced in nuclear interaction, C is primary produced in stars. B/C is sensitive tothe diffusion constant
3He/4He ratio is sensitive to the density of the ISM
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 19
AMS02 : detector performanceAMS02 : detector performance
Acceptancesdefined by selection cuts during reconstruction Antiprotons:
A(<16 GeV) ∼ 1200cm 2sr>16GeV ∼ 330 cm 2
Rejection e- ∼ 10 4p ∼ 10 6
Preliminary
Positrons:
Acceptance ∼ 550 cm 2 srRejection e- ∼ 10 3
p ∼ 10 5
Gamma (ECAL mode):Acceptance ~ 600 cm 2 srRejection e+ - ~ 10 4
p ~ 10 5
Gamma (Conversion mode):Acceptance ~ 550 cm 2 sr
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 20
Expected statistics after oneyear of AMS-02 operations
July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 21
Summary
AMS is a High Energy Physics detector in space foreseen to operate on the ISS for 3 years
Complete detector in 2006
The cosmic rays, including gamma rays, will be measured with a high accuracy from the GeV to the TeVrange
Unique opportunity to perform Dark Matter searches